A species of parasitic aliens descends on Earth and quickly infiltrates humanity by entering the brains of vulnerable targets; insatiable beings that gain total control of their host and are capable of transforming themselves to feed on unsuspecting prey. High school student Shinichi Izumi falls victim to one of these parasites, but the creature fails to take over his brain and ends up in his right hand.
Bullies often target someone frail and weak—someone exactly like Yûgi Muto. He treasures his Millennium Puzzle, an ancient Egyptian artifact that was brought into his grandfather's game shop. Believing that solving the puzzle will grant him his wish, he completes the puzzle, unleashing a new personality within him, the soul of the "King of Games." The new personality named Yami Yûgi is the exact opposite of Yûgi. Upon any injustice toward him, Yami Yûgi takes over Yûgi's body and forces the opponent into a "Shadow Game".
After going their separate ways, Scooby-Doo, Shaggy, Velma, Daphne, and Fred reunite to investigate the ghost of Moonscar the pirate on a haunted bayou island, but it turns out the swashbuckler's spirit isn't the only creepy character on the island. The sleuths also meet up with cat creatures and zombies... and it looks like for the first time in their lives, these ghouls might actually be real.
